Human Exposure to Herbicide Up 500 Percent in 20 Years

SAN DIEGO (CN) – Urinary samples from a group of older Southern Californians reveal exposure to the weed killer glyphosate has increased roughly 500 percent since the introduction of genetically modified crops.

The use of glyphosate, a key ingredient in Monsanto’s herbicide Roundup, is now 15 times higher than it was in 1994, when glyphosate-tolerant crops were first developed. Despite this increased use, however, concerns remain over how exposure to the weed killer impacts human and animal health.

To measure human exposure to glyphosate, a team of researchers analyzed urinary samples from 100 Southern California residents participating in a long-term health and behavior study. The team’s results were published Tuesday in the Journal of the American Medical Association.

“The data compares excretion levels of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in the human body over a 23-year time span, starting in 1993, just before the introduction of genetically modified crops into the United States,” said lead author Paul J. Mills, a professor at the University of California, San Diego.

The researchers examined samples the participants provided during five clinic visits from 1993 to 1996 and 2014 to 2016.

“What we saw was that prior to the introduction of genetically modified foods, very few people had detectable levels of glyphosate,” Mills said. “As of 2016, 70 percent of the study cohort had detectable levels.”

Among participants whose samples featured detectable levels of these chemicals, the mean volume of glyphosate spiked from 0.203 micrograms per liter, or ug/l, in the 1993-1996 samples to 0.449 ug/l in 2014-2016. The average level of AMPA increased from 0.168 ug/l in 1993-1996 to 0.401 ug/l in 2014-2016.

While little research has been done on the impact of glyphosate on human health, animal studies show that consistent exposure to the glyphosate-based herbicides can lead to problems, according to Mills. The team points to other studies that have shown feeding animals even a small dose of the weed killer resulted in liver disorders that resemble nonalcoholic fatty liver disease in humans.

“The public needs to be better informed of the potential risks of the numerous herbicides sprayed onto our food supply so that we can make educated decisions on when we need to reduce or eliminate exposure to potentially harmful compounds,” Mills said.

Glyphosate has typically been used on genetically modified soy and corn, but it is also sprayed on a significant portion of oats and wheat grown in the United States.

“Our exposure to these chemicals has increased significantly over the years but most people are unaware that they are consuming them through their diet,” Mills said.